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Siemens S5-135U/155U User Manual

Page 408

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9-26

System Manual

C79000-G8576-C199-06

The resolution with Pt 100 resistance thermometers is approximately 0.25

o

C.

1 ohm

10 units

Units Resistance in

ohms

Temper-

ature in

Byte 0

Byte 1

ohms

ature in

o

C

7

S

6

2

11

5

2

10

4

2

9

3

2

8

2

2

7

1

2

6

0

2

5

7

2

4

6

2

3

5

2

2

4

2

1

3

2

0

2

A

1

E

0
OV

4096 400.0

0

1

1

1 1 1 1 1 1 1 1 1 1 0/1 0/1 1

Overflow

4095
2049

399.90

200.98

269.1

0

0

1

1

1

0

1

0

1

0

1

0

1

0

1

0

1

0

1

0

1

0

1

0

1

1

0/1

0/1

0/1

0/1

0

0

Overrange

2048
2047

200.0

199.90

266.5

266.0

0

0

1

0

0

1

0

1

0

1

0

1

0

1

0

1

0

1

0

1

0

1

0

1

0

1

0/1

0/1

0/1

0/1

0

0

1024
1023

100.00

99.90

0

–0.2

0

0

0

0

1

0

0

1

0

1

0

1

0

1

0

1

0

1

0

1

0

1

0

1

0

1

0/1

0/1

0/1

0/1

0

0

Rated range

1
0

0.098

0.0

0

0

0

0

0

0

0

0

0

0

0

0

0

0

0

0

0

0

0

0

0

0

0

0

1

0

0/1

0/1

0/1

0/1

0

0

A = Active bit
E = Error bit
OV = Overflow bit
S = Sign

When Pt 100 resistance thermometers are connected, the maximum
temperature in the rated range is 266

o

C. If it can be ensured that the

temperature does not exceed 850

o

C, the input value may extend into the

overrange. The resolution is then 4095 units. Unused inputs can be utilized
for voltage measurements in the 500 mV range (see front connector
assignments).

In addition to the standard Pt 100 range, there is an extended Pt 100 range on
the 460 analog input module. You can select this with the mode switch.

The following is printed on the cover of the module to set the Pt 100 mode:

Standard range: “resistance thermometer uncompensated full range”
Extended range: “resistance thermometer compensated low range”

In this range, the basic resistance of the Pt 100 at 0

o

C (100 ohms) is

compensated for on the module. As in the standard range, the Pt 100 is fed
with a constant current of 2.5 mA. Using the overrange (- 100 mV to + 100
mV), this results in a temperature range of approx. -100

°

C to + 100

°

C.

This measuring range of 200

°

C is resolved to 8192 units with the correct

sign for the temperature. One unit thus corresponds to approximately 0.025

°

C. If you select the extended Pt 100 range, you can use all 8 analog inputs in

this range only.

You should only use the 6ES5 498-1AA11 range card (

$ 50 mV/500 mV).

Measured-Value
Representation for
Resistance
Thermometers in
the Standard Pt
100 Range

Extended Pt 100
Range

Analog Input/Output Modules